Reversing valve assemblies for centralized lubricating systems



y 11, 1957 HIROSHI FUJITA 3,

REVERSING VALVE ASSEMBLIES FOR CENTRALIZED LUBRICATING SYSTEMS Filed April 10, 1964 United States Patent 3,330,380 REVERSING VALVE ASSEMBLIES FOR CEN- TRALIZED LUBRICATING SYSTEMS Hiroshi Fujita, Shiga-ken, Japan, assignor to Daikin Kogyo Co., Ltd., Osaka, Japan, a corporation of Japan Filed A r. 10, 1964, Ser. No. 358,831 Claims priority, application Japan, Apr. 12, 1963, 38/ 19,212 4 Claims. (Cl. 184-7) This invention relates generally to single-line type centralized lubricating systems including a single oil pressure pump and a plurality of distributing valves arranged to supply appropriate quantities of lubricating oil to many areas to be lubricated. Particularly, the present invention relates to switching valve assemblies as one of the most essential parts of such centralized lubricating system and provides an improved reversing valve assembly constructed upon an entirely novel conception.

One of the objects of the present invention is to provide a novel reversing valve assembly for use in a centralized lubricating system which comprises a main valve, pilot valve and an accumulator plunger associated with said mechanisms so as to operate to store fluid returning to the valve assembly at the end of each distributing cycle of operation to actuate the pilot valve when a predetermined pressure has been reached. The switching valve assembly according to the present invention is normally connected on one hand, to the opposite ends of a loop of conduit which includes a plurality of seriesconnected distributor valves and, on the other hand, to an oil pressure pump and is automatically operable to direct the fluid therefrom into the conduit alternately through its two end connections with the valve assembly.

The present invention will now be described in further detail with reference to the accompanying drawing, which diagrammatically illustrates one preferred form of reversing valve assembly embodying the invention.

Referring to the drawing, the valve assembly has a casing body A which has formed therein three cylindrical plunger-accommodating cavities a, b and c and two spaced openings 5 and 5 to be connected with the opposite ends of the fluid circuit 6 including distributor valves D. Each of the openings 5 and 5 alternately serve as an outlet and a return port of the valve assembly, as will be described below. Slidably fitted in one of the cavities a is a main plunger 1 which operates to direct fluid from an oil pressure pump P to the distributor circuit alternately through the two openings 5 and 5', which are connected with the cavity a as shown. Slidably fitted in another cavity b is a pilot plunger 2 which is operable to limit the stroke movement of the main plunger 1. Also slidably fitted in the third cavity c is an accumulator or pressure-storing plunger 3 which aids the pilot plunger in its movement and also serves to store or take up the surges of pressure energy appearing in the return opening 5 or 5'.

In order to associate these plungers with each other in a manner to maintain an appropriate operative relationship therebetween, a number of fluid passages 7, 8, 9, 10, 11, 12 and 13 are formed in the casing, as shown. Passage 7 receives fluid from pump P and delivers it to both cavities a and b at points intermediate ice the ends thereof. Passage 8 interconnects the left-hand end of cavity a and a point in cavity b located slightly to the left of the opening of the passage 7 to the cavity b. Passage 9 connects cavity a with the right-hand ends of cavities b and c. Passage 10 interconects the righthand end of cavity a and a point in cavity b located slightly to the right of the opening for the passage 7 in the cavity b in symmetrical relation to passage 7. Passages 10 and 11 are formed in symmetrical relation to the passages 8 and 9, respectively, as seen in the drawing. Passage 12 is connected with a line leading to an oil reservoir tank T and opens to the right and left portions of cavity a to receive oil therethrough and return it to the oil tank T. Finally, passage 13 is also connected with a line leading to the oil tank T and opens to the right and left portions of the cavity b to receive oil therethrough and return it to the oil tank T.

As shown, the main and pilot plungers 1 and 2 are shaped symmetrically, plunger 1 having formed therein two pairs of spaced reduced-diameter portions and plunger 2 having one pair of reduced-diameter portions. The pilot plunger 2 is also formed near each of its ends with pairs of closely spaced peripheral grooves of generally V-shaped cross section to receive spring-biased detent balls 4 and 4' which are received in bores formed in the casing body as illustrated. The accumulator plunger 3 is cylindrical wit-h a pair of compression springs 14 and 14' arranged between the plunger and the adjacent end walls of the cavity c. An indicator rod 15 is secured to one end of the main plunger 1 substantially in axial alignment therewith for indicating the positioning of the main plunger 1.

Of course, the oil pressure pump P is connected with the oil tank T to receive oil therefrom and each of distributor valves D is operable when fed with fluid to distribute the fluid to associated areas to be lubricated, asindicated by the arrows. The arrows annexed to the lines leading from and to the pump P and oil tank T indicate the direction of flow in the associated lines.

The operation of the switching valve assembly will next be described.

Upon operation of the pump P, lubricant is delivered into passage 7 and directed to flow past the main and pilot plungers 1 and 2. The lubricant flow passing the pilot plunger 2 proceeds into passage 8 and through it enters the left-hand end of the cavity a to urge the main plunger 1 housed therein rightward. On the other hand, the lubricant which enters the cavity a through passage 7 flows past the main plunger 1 and through the opening 5 enters the circuit 6 to operate the distributor valves D therein successively. The fluid flowing out of the final distributor valve D returns into the opening 5, now serving as a return port. The returning fluid again flows past the main plunger 1 and enters passage 9 to flow into cavities b and c at the right-hand ends thereof. The returning fluid will actuate the accumulator plunger 3 to the left until a definite amount of fluid is stored to create a predetermined pressure in the free space just formed in the right-hand end of the cavity 0. On the other hand, as the fluid in the passage 9 reaches the predetermined pressure, it actuates the pilot plunger 2 to the left overcoming the restraining force offered by the spring biased detent balls 4 and 4'. On the leftward stroke of the pilot 3 plunger,' as the passage 7 begins to communicate with passage 10 thereby to allow pressure fluid from pump P to enter the passage 10, the fluid returning into the valve assembly through the opening 5 is reduced in pressure because the connection between passage 7 and opening 5 has simultaneously been closed.

Under these circumstances, the fluid pressure urging the pilot plunger to the left seemingly might fall off to a value insufficient to shift it leftward, but actually it is intensified by the fluid pressure previously stored in the end space of cavity C and now flowing back through passage 9 under the action of spring 14 to act effectively upon the right-hand end of the pilot plunger 2 so that the latter never dwells midway of its leftward stroke but is shifted to its extreme left position.

During the above operation, it will be observed that the left ends of cavities b and c communicate with oil tank T by way of passage 11, main plunger 1 and passage 12. After completion of the leftward stroke of pilot plunger 2, the pressure fluid from oil pump P flows through passages 7 and 10 to act upon the main plunger 1 at its right-hand end so that the plunger 1 is moved leftward. At this time, it will be noted that the cavity space on the left of the main plunger 1 is in communication with oil tank T by way of passages 8 and 13. At the end of the leftward stroke of the main plunger 1, the passage 7 is connected with the opening 5', the passage 11 being connected with the opening 5, where high fluid pressure has remained. The remaining pressure, however, is immediately absorbed in the left-hand space of the cavity through the passage 11, since pressure in the cavity space has been reduced upon completion of the leftward stroke of the main plunger 1 because of the fact that the accumulator plunger 3 is then being urged rightward under the action of spring 14 to restore its normal medial position against the weaker force of the extended spring 14', the right end space of the cavity 0 being now in communication with the oil tank T by way of passage 9, main plunger 1 and passage 12. It will be noted that the switching valve assembly has nOW completed its switching operation to get ready to start another cycle of distributing operation, in which the openings and 5' will serve as a return and an outlet port, respectively, of the switching valve assembly, as contrasted to the preceding distributing cycle.

In the illustrated embodiment, the main plunger 1 is desirably extended at one end to form an indicator rod 15, which is exposed to the outside of the casing body A enabling the attendant to observe the operation of the switching valve assembly.

Moreover, according to the present invention, since the fluid pressure remaining in the opening area 5 or 5' toward the end of each distributing cycle of operation is effectively taken up by the accumulator plunger 3, the delivery pressure of the fluid pump P can have at all times a predetermined value.

When the reversing valve of the present invention, which operates as described hereinbefore, is provided in a single-line type centralized lubricating system, the pres- .sure oil, for instance, is directed from the opening 5 to the other opening 5, i.e., to the right-hand end of cavity of the pilot plunger 2 where the pressure is built up to a predetermined value by the function of the spring-biassed detent valves 4 and 4', and by this time the pressure at the opening 5 has reached a considerably high value. The actuation of the pilot plunger 2 here will switch the functions of the respective parts in the reverse way, with the opening 5' serving as an outlet and the opening 5 as a return port, as has been explained previously. In the next oil supply operation, the return port 5 is the place where the return pressure, which will be the reversing pressure for the pilot plunger 2, is sensed and the pressure thereat cannot, therefore, be released, for example, to a tank T. However, the pressure at the opening 5 still remains at a high value as above described, which must be reduced because even a slight pressure which remains thereat will be accumulated one after another as the switching operation is repeated, but on the other hand, the pressure, as has been described, cannot be released to the tank.

The accumulator plunger 3 and the compression springs 14, 14' in the present invention serve an unique function of facilitating a reduction in pressure within the cylinder at the time of switching in which the remaining high pressure is absorbed. On account of this function, it is possible to obtain the pressure diiference needed for the operation of the feeders and, consequently, a reversing valve for single-line type centralized lubricating systems of the present invention is achieved. The remaining pressure thus absorbed in the accumulator 3 will not continuously be accumulated therein, as the accumulator communicates with the tank T in the next cycle of distributing operation.

As apparent from the foregoing description, the novel feature of the present invention lies essentially in the provision of an accumulator plunger 3, which not only ensures proper operation of the pilot plunger 2 but is also operable to store the high fluid pressure appearing upon completion of each switching cycle in the region of that opening into which fluid returns from the circuit in the preceding distributing cycle of operation. It will be understood, therefore, that, though one embodiment of the invention has been shown and described herein which has a reversing mechanism including a pilot and a main plunger, the accumulator plunger of the present invention may also be used in combination with other forms of switching mechanism which are constructed and function in substantially the same manner as described herein.

What is claimed is: f

1. In a centralized lubricating system including a distributing circuit, a reversing valve assembly connected with the opposite ends of said distributing circuit and operable to direct fluid into said distributing circuit alternately through the opposite ends thereof, said reversing valve assembly comprising reciprocating pilot plunger valve means, reciprocating main plunger valve means, a closed accumulator cylinder having a reciprocating accumulator piston therein, conduit means for establishing communication between a pump means and one end of the distributing circuit and for establishing communication with a tank and the other end of the distributing circuit through the main plunger valve in one position and for reversing said order of communication when the main plunger valve is reciprocated to another position, said accumulator cylinder having a pair of axially spaced ports, said piston being movable between said ports, bidirectional biassing means urging the piston toward a medial position between said ports, conduit means for establishing communication between said pump means and said main plunger valve through said pilot plunger valve to reciprocate the main plunger valve between said one and another positions in response to reciprocation of the pilot plunger valve between two positions, conduit means for establishing communication between the respective ends of the distributing circuit and the pilot plunger valve and a respective alternative port insaid accumulator cylinder through the main plunger valve to urge the pilot plunger valve toward its respective other position and to urge movement of the accumulator piston in opposition to said biassing means, said last-mentioned conduit means also establishing communication between the other respective port in said accumulator cylinder and a tank until said pilot plunger valve has initiated movement toward said respective other position 2. The invention as defined in claim 1, wherein said reversing 'valve assembly also includes detent means for said pilot plunger valve whereby movement of said valve in either reciprocatory direction is restrained until a predetermined force is exerted onsaid accumulator piston by said biassing means.

3. The invention as defined in claim 1, wherein said bi-directiona] biassing means comprises a pair of coil springs positioned in said closed cylinder between the respective ends of the cylinder and piston.

4. A reversing valve assembly according to claim 2, in that the pilot plunger is formed toward each of its ends with a pair of closely spaced peripheral grooves of generally V-shaped cross section to received a spring biassed detent ball, which is received in a bore formed in the casing body.

6 References Cited UNITED STATES PATENTS 2,794,518 6/1957 Pawling 184-7 2,856,023 10/ 1958 Graves 1847 FOREIGN PATENTS 894,404 4/1962 Great Britain.

10 LAVERNE D. GEIGER, Primary Examiner.

E. EARLS, Assistant Examiner. 

1. IN A CENTRALIZED LUBRICATING SYSTEM INCLUDING A DISTRIBUTING CIRCUIT, A REVERSING VALVE ASSEMBLY CONNECTED WITH THE OPPOSITE ENDS OF SAID DISTRIBUTING CIRCUIT AND OPERABLE TO DIRECT FLUID INTO SAID DISTRIBUTING CIRCUIT ALTERNATELY THROUGH THE OPPOSITE ENDS THEREOF, SAID REVERSING VALVE ASSEMBLY COMPRISING RECIPROCATING PILOT PLUNGER VALVE MEANS, RECIPROCATING MAIN PLUNGER VALVE MEANS, A CLOSED ACCUMULATOR CYLINDER HAVING A RECIPROCATING ACCUMULATOR PISTON THEREIN, CONDUIT MEANS FOR ESTABLISHING COMMUNICATION BETWEEN A PUMP MEANS AND ONE END OF THE DISTRIBUTING CIRCUIT AND FOR ESTABLISHING COMMUNICATION WITH A TANK AND THE OTHER END OF THE DISTRIBUTING CIRCUIT THROUGH THE MAIN PLUNGER VALVE IN ONE POSITION AND FOR REVERSING SAID ORDER OF COMMUNICATION WHEN THE MAIN PLUNGER VALVE IS RECIPROCATED TO ANOTHER POSITION, SAID ACCUMULATOR CYLINDER HAVING A PAIR OF AXIALLY SPACED PORTS, SAID PISTON BEING MOVABLE BETWEEN SAID PORTS, BIDIRECTIONAL BIASSING MEANS URGING THE PISTON TOWARD A MEDIAL POSITION BETWEEN SAID PORTS, CONDUIT MEANS FOR ESTABLISHING COMMUNICATION BETWEEN SAID PUMP MEANS AND SAID MAIN PLUNGER VALVE THROUGH SAID PILOT PLUNGER VALVE TO RECIPROCATE THE MAIN PLUNGER VALVE BETWEEN SAID ONE AND ANOTHER POSITIONS IN RESPONSE TO RECIPROCATION OF THE PILOT PLUNGER VALVE BETWEEN TWO POSITIONS, CONDUIT MEANS FOR ESTABLISHING COMMUNICATION BETWEEN THE RESPECTIVE ENDS OF THE DISTRIBUTING CIRCUIT AND THE PILOT PLUNGER VALVE AND A RESPECTIVE ALTERNATIVE PORT IN SAID ACCUMULATOR CYLINDER THROUGH THE MAIN PLUNGER VALVE TO URGE THE PILOT PLUNGER VALVE TOWARD ITS RESPECTIVE OTHER POSITION AND TO URGE MOVEMENT OF THE ACCUMULATOR PISTON IN OPPOSITION TO SAID BIASSING MEANS, SAID LEAST-MENTIONED CONDUIT MEANS ALSO ESTABLISHING COMMUNICATION BETWEEN THE OTHER RESPECTIVE PORT IN SAID ACCUMULATOR CYLINDER AND A TANK UNTIL SAID PILOT PLUNGER VALVE HAS INITIATED MOVEMENT TOWARD SAID RESPECTIVE OTHER POSITION. 